Samarium Diiodide Mediated Reactions in Total Synthesis

Introduced by Henri Kagan more than three decades ago, samarium diiodide (SmI₂) has found increasing application in chemical synthesis. This single‐electron reducing agent has been particularly useful in C? C bond formations, including those found in total synthesis endeavors. This Review highlights selected applications of SmI₂ in total synthesis, with special emphasis on novel transformations and mechanistic considerations. The examples discussed are both illustrative of the power of this reagent in the construction of complex molecules and inspirational for the design of synthetic strategies toward such targets, both natural and designed.     

Total Synthesis of Sporolide B

An ocean of discovery : The first total synthesis of the highly oxygenated, marine‐derived, natural product sporolide B has been achieved through a convergent strategy. The key steps involve a ruthenium‐catalyzed [2+2+2] cycloaddition to assemble the indene structural motif and a thermally induced Diels–Alder‐type reaction to forge the macrocycle (see scheme).

     

Origins of selectivity in pericyclic reaction cascades for the synthesis of gambogin and lateriflorone

[reaction: see text] Quantum mechanical calculations demonstrate that the second step of a Claisen-Diels-Alder reaction cascade controls regioselectivity that gives advanced intermediates for the synthesis of gambogin and 1-O-methyllateriflorone.     

Analysis of polyphenols using capillary zone electrophoresis--determination of the most effective wine sample pre-treatment method

A simple CZE method has been developed for the simultaneous determination of eight polyphenolic compounds. The influence of several experimental conditions such as buffer (concentration and pH) and temperature were studied. Optimum separation was achieved in less than 25 min by using a BGE of 50 mM Na(2)B(4)O(7) and 10 mM Na(2)HPO(4) at pH 9.6, a temperature of 25°C and an applied voltage of 25 kV. Good linearities for all eight analytes were obtained with correlation coefficients higher than 0.99. The LODs were between 0.03 and 5.05 μg/mL and the RSD values of the migration times were found to be less than 1%. The optimal separation conditions were then used for the identification and the quantitation of polyphenolic compounds in Cypriot wine samples using six different sample preparation procedures. In particular, two direct injection methods (without any extraction step), three different liquid-liquid extraction procedures and an SPE procedure were examined. These sample pre-treatment methods were also compared in order to determine the one that is the most effective, in regard to analyte recovery, time, difficulty, and reproducibility. Liquid-liquid extraction using diethyl ether as the organic solvent proved to be the most effective.     

Cascade reactions in total synthesis

The design and implementation of cascade reactions is a challenging facet of organic chemistry, yet one that can impart striking novelty, elegance, and efficiency to synthetic strategies. The application of cascade reactions to natural products synthesis represents a particularly demanding task, but the results can be both stunning and instructive. This Review highlights selected examples of cascade reactions in total synthesis, with particular emphasis on recent applications therein. The examples discussed herein illustrate the power of these processes in the construction of complex molecules and underscore their future potential in chemical synthesis.